Fastest integer types of at least 64 bits

Names specified here
Name	Description	Notes				Source
`atomic_int_fast64_t`	Atomic integer type		?		T	`<stdatomic.h>`		C11
`atomic_uint_fast64_t`	Atomic integer type		?		T	`<stdatomic.h>`		C11
`INT_FAST64_MAX`	Maximum value of `int_fast64_t`	L		M		`<stdint.h>`	C99	C11
`INT_FAST64_MIN`	Minimum value of `int_fast64_t`	L		M		`<stdint.h>`	C99	C11
`int_fast64_t`	Fastest signed integer type with at least 64 bits	L			T	`<stdint.h>`	C99	C11
`PRIdFAST64`	Decimal output conversion specifier for `int_fast64_t`			M		`<inttypes.h>`	C99	C11
`PRIiFAST64`	Decimal output conversion specifier for `int_fast64_t`			M		`<inttypes.h>`	C99	C11
`PRIoFAST64`	Octal output conversion specifier for `uint_fast64_t`			M		`<inttypes.h>`	C99	C11
`PRIuFAST64`	Decimal output conversion specifier for `uint_fast64_t`			M		`<inttypes.h>`	C99	C11
`PRIXFAST64`	Hexdecimal output conversion specifier for `uint_fast64_t`			M		`<inttypes.h>`	C99	C11
`PRIxFAST64`	Hexdecimal output conversion specifier for `uint_fast64_t`			M		`<inttypes.h>`	C99	C11
`SCNdFAST64`	Decimal input conversion specifier for `int_fast64_t`			M		`<inttypes.h>`	C99	C11
`SCNiFAST64`	General input conversion specifier for `int_fast64_t`			M		`<inttypes.h>`	C99	C11
`SCNoFAST64`	Octal input conversion specifier for `uint_fast64_t`			M		`<inttypes.h>`	C99	C11
`SCNuFAST64`	Decimal input conversion specifier for `uint_fast64_t`			M		`<inttypes.h>`	C99	C11
`SCNxFAST64`	Hexdecimal input conversion specifier for `uint_fast64_t`			M		`<inttypes.h>`	C99	C11
`UINT_FAST64_MAX`	Maximum value of `uint_fast64_t`	L		M		`<stdint.h>`	C99	C11
`uint_fast64_t`	Fastest unsigned integer type with at least 64 bits	L			T	`<stdint.h>`	C99	C11

uint_fast64_t and int_fast64_t are the fastest integer types of at least 64 bits. uint_fast64_t is unsigned, and has the range zero to UINT_FAST64_MAX, which is at least [0, +18446744073709551615]. int_fast64_t is signed, and has the range INT_FAST64_MIN to INT_FAST64_MAX, which is at least [−9223372036854775807, +9223372036854775807].

The following macros can be used in the fmt argument of printf to print arguments of types uint_fast64_t and int_fast64_t:

PRIuFAST64
PRIoFAST64
PRIxFAST64
PRIXFAST64
PRIdFAST64
PRIiFAST64

The following macros can be used in the fmt argument of scanf to scan arguments of types uint_fast64_t * and int_fast64_t *:

SCNuFAST64
SCNoFAST64
SCNxFAST64
SCNdFAST64
SCNiFAST64

atomic_uint_fast64_t is an alias for _Atomic uint_fast64_t. atomic_int_fast64_t is an alias for _Atomic int_fast64_t.

Related types:

uint64_t
int64_t
uint_least64_t
int_least64_t
uint_fast64_t
int_fast64_t

Property		`uint_fast64_t`	`int_fast64_t`
Minimum width (bits)		64
Lowest value		0	≤−9223372036854775807
Highest value		≥+18446744073709551615	≥+9223372036854775807
`printf`	base 10	`"%" PRIuFAST64`	`"%" PRIdFAST64` or `"%" PRIiFAST64`
	base 8	`"%" PRIoFAST64`
	upper-case base 16	`"%" PRIXFAST64`
	lower-case base 16	`"%" PRIxFAST64`
`scanf`	base 10	`"%" SCNuFAST64`	`"%" SCNdFAST64`
	base 8	`"%" SCNoFAST64`
	base 16	`"%" SCNxFAST64`
	base 16, 8 or 10 by prefix		`"%" SCNiFAST64`